Year years 1960 43.41506249275055 1961 46.04142908192899 1962 49.50146708790524 1963 49.94618767203265 1964 50.50387469171235 1965 50.30683814001259 1966 51.02183237360006 1967 51.58853610705107 1968 52.31311462098448 1969 52.80672824473408 1970 53.135939968928454 1971 53.25840521617048 1972 54.383449676666515 1973 55.07021927250815 1974 55.57473693250409 1975 56.17156619472354 1976 56.770972311121014 1977 57.37178773167856 1978 57.855119682816884 1979 58.37570820879403 1980 58.85475536797934 1981 59.28095358800471 1982 59.692963770660796 1983 60.03741245099396 1984 60.42165628224499 1985 60.79356051378365 1986 61.22729644377464 1987 61.59348261622924 1988 61.82669585231535 1989 62.25482448466325 1990 62.48021371042564 1991 62.66778271305544 1992 63.024405864312484 1993 63.33643385046774 1994 63.62470503947559 1995 63.869886375177806 1996 64.10841585962983 1997 64.46213355848434 1998 64.7777100608117 1999 65.16835217110439 2000 65.52769384313012 2001 65.93218125490579 2002 66.26808451478166 2003 66.60857956526459 2004 66.8346393807025 2005 67.24236484049655 2006 67.61849866305356 2007 67.8839073410554 2008 68.06588486244918 2009 68.48634511059687 2010 68.79079388049685 2011 69.14772900732018 2012 69.46981939852634 2013 69.7932388843787 2014 70.12815074030104 2015 70.41620365696785 2016 70.69783945147576 2017 70.92714873111596 2018 71.21367254090613 2019 71.41327999189957 2020 70.74702272635724 2021 69.72408438296294 2022 70.39558704146918